The present application relates to a circuit substrate, a method of manufacturing such a circuit substrate, and an electronic component, and more specifically to a circuit substrate that is suitable for use in performing a flip-chip mounting, a method of manufacturing such a circuit substrate, and an electronic component.
A flip-chip mounting has been utilized as one of methods for mounting a chip such as an LSI on a circuit substrate. Further, as one of flip-chip mounting methods, a method has been in use that forms solder bumps on a circuit substrate side for connection with terminals on a chip side (for example, see Japanese Patent Nos. 3420076 and 3362079). Formation of solder bumps on a circuit substrate allows a chip to be mounted on a circuit substrate at lower loading even in the event of variation in the heights of circuit substrate patterns as compared with a case where solder bumps are formed on front edges of chip terminals.
Further, the technologies that are mentioned in Japanese Patent Nos. 3420076 and 3362079 have been elaborated to increase the accuracy of positioning and shapes of solder bumps to be formed on a circuit substrate. More specifically, Japanese Patent No. 3420076 has proposed a method in which connection pads of width greater than any other portion are formed on a wiring pattern, and solder bumps are formed on such connection pads. On the other hand, Japanese Patent No. 3362079 has proposed a method in which an adhesive film is formed on a circuit substrate pattern, and solder bumps are formed in a manner of giving attachment of solder powder to such a film and applying heat thereto.